This invention relates to a pulse generator for use in a noise pulse canceller. The pulse generator is specifically useful in a radio receiver for an automobile or the like.
In a noise pulse canceller, a pulse generator is used together with a gate circuit to which a circuit input signal is supplied through a low-pass filter. The input signal is supplied to the pulse generator through a high-pass filter. A conventional pulse generator is usually a monostable multivibrator for supplying the gate circuit with a gating pulse during presence of a noise pulse in the circuit input signal. The gate circuit interrupts the circuit input signal during presence of the gating pulse and produces an output signal free from the noise pulse. It is necessary that the gating pulse should last during existence of the noise pulse, which has a width irregularly variable in general. Moreover, the width of the noise pulse tends to be shortened and widened by the high-pass and low-pass filters, respectively, as will later be described with reference to a few figures of the accompanying drawing. Accordingly, it is difficult to completely suppress the noise pulse by the use of the conventional pulse generator.